Field of the Invention
The present invention relates to a drive motor of an environmentally-friendly vehicle, and more particularly, to a cooling structure of a drive motor for cooling heat that is generated by the drive motor.
Description of Related Art
In general, hybrid vehicles or electric vehicles, which are usually called environmentally-friendly vehicles, can be driven by an electric motor (hereafter, also referred to as a “drive motor”) acquiring torque from electric energy of a battery.
The drive motor includes a stator and a rotor, in which the stator is disposed in a motor housing and the rotor is disposed at a side of the stator with a gap therebetween. The stator includes a stator core that is an electric steel plate and a coil wound around the stator core.
Meanwhile, the drive motor generates a large amount of heat depending on the current applied to the coil of the stator. Accordingly, cooling is necessary for preventing damage and deterioration of efficiency of the driving motor due to heat and continuously securing stable operation of the drive motor.
In particular, cooling a drive motor such as a permanent magnet synchronous motor (PMSM) is very important in terms of efficiency of the motor and protection of main parts (a permanent magnet, a coil, etc.). Cooling a drive motor is an important factor that determines the performance and efficiency of a drive motor. That is, the permanent magnet and the coil in a drive motor may influence the performance of the motor, depending on temperature.
As methods of cooling drive motors, there are an oil cooling type that uses transmission oil (ATF) and a water cooling type that uses cooling water. For example, according to a structure for cooling a drive motor using the oil cooling type, a stator core is fixed to a motor housing and also a support ring for cooling the stator core is disposed between the stator core and the motor housing.
Accordingly, heat generated from the drive motor transfers to the support ring through the stator core and is dissipated through the support ring. According to the structure for cooling a drive motor, oil flows through a channel in the support ring, where it is possible to cool a drive motor with a maximum amount of heat that is dissipated through the support ring.
However, according to the structure for cooling a drive motor using the oil cooling type, since a drive motor is indirectly cooled by the oil flowing through the channel in the support ring, there is a limit in improving the performance of cooling a drive motor.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.